diff --git a/trunk/src/com/jpexs/decompiler/flash/gui/GenericTagTreePanel.java b/trunk/src/com/jpexs/decompiler/flash/gui/GenericTagTreePanel.java
index b92fe6446..f289be722 100644
--- a/trunk/src/com/jpexs/decompiler/flash/gui/GenericTagTreePanel.java
+++ b/trunk/src/com/jpexs/decompiler/flash/gui/GenericTagTreePanel.java
@@ -601,7 +601,16 @@ public class GenericTagTreePanel extends GenericTagPanel {
                 return 0;
             }
             Field field = fnode.field;
-            if (ReflectionTools.needsIndex(field) && (fnode.index == -1)) { //Arrays ot Lists
+            if (ReflectionTools.needsIndex(field) && (fnode.index == -1)) { //Arrays or Lists
+                try {
+                    if (field.get(fnode.obj) == null) {
+                        // todo: instanciate the (Array)List or Array to allow adding items to it
+                        return 0;
+                    }
+                } catch (IllegalArgumentException | IllegalAccessException ex) {
+                    return 0;
+                }
+
                 return ReflectionTools.getFieldSubSize(fnode.obj, field);
             }
             parent = fnode.getValue();